Exercise 05 — App Upgrade via GitOps

Time: ~15 min (often done as the final step of Exercise 04) Goal: Reflect on the complete GitOps loop you've built and optionally run another upgrade cycle.

What you built

You now have a fully functioning GitOps platform:

Git repo (source of truth)
      │
      │  ArgoCD polls every 3 min (or on Refresh)
      ▼
ArgoCD (GitOps engine)
      │  detects drift between Git and cluster
      ▼
Kubernetes cluster
      │  MetalLB assigns LAN IP to Ingress-Nginx
      ▼
Ingress-Nginx (routes by hostname)
      │
      ├─► podinfo.192.168.56.200.nip.io  →  podinfo Deployment
      └─► argocd.192.168.56.200.nip.io   →  ArgoCD UI

And a CI pipeline that closes the loop:

Tekton PipelineRun
      │
      ├─ validate manifests
      ├─ bump image tag in deployment.yaml
      └─ git push
            │
            ▼
      ArgoCD detects commit → syncs → rolling update

Reflect: What makes this "GitOps"?

Git is the source of truth — the cluster state is always derived from this repo
No manual kubectl apply — all cluster changes go through Git commits
Drift detection — if someone manually changes something in the cluster, ArgoCD reverts it
Audit trail — every cluster change has a corresponding Git commit
Rollback = git revert — no special tooling needed

Optional: Try a manual upgrade

If the pipeline already bumped podinfo to 6.7.0, try a manual downgrade to see the loop in reverse:

# Edit the image tag back to 6.6.2
vim manifests/apps/podinfo/deployment.yaml
# Change: ghcr.io/stefanprodan/podinfo:6.7.0
# To:     ghcr.io/stefanprodan/podinfo:6.6.2

git add manifests/apps/podinfo/deployment.yaml
git commit -m "chore: downgrade podinfo to 6.6.2 for demo"
git push

Watch ArgoCD sync in the UI, then verify:

curl http://podinfo.192.168.56.200.nip.io | jq .version
# "6.6.2"

Now upgrade again via the pipeline:

kubectl delete pipelinerun bump-podinfo-to-670 -n tekton-pipelines
kubectl apply -f manifests/ci/pipeline/pipelinerun.yaml

Optional: Test drift detection

ArgoCD's selfHeal: true means it will automatically revert manual cluster changes.

Try bypassing GitOps:

# Change the image tag directly in the cluster (not via Git)
kubectl set image deployment/podinfo podinfo=ghcr.io/stefanprodan/podinfo:6.5.0 -n podinfo

Watch the ArgoCD UI — within seconds you'll see the podinfo app go OutOfSync, then ArgoCD reverts it back to whatever tag is in Git. The cluster drifted; GitOps corrected it.

Summary

Component	Purpose	How deployed
k3s	Kubernetes	Vagrantfile
ArgoCD	GitOps engine	bootstrap.sh → self-manages
MetalLB	LoadBalancer IPs	ArgoCD
Ingress-Nginx	HTTP routing	ArgoCD
podinfo	Demo app	ArgoCD
Tekton	CI pipeline	ArgoCD

What's next

If you have time, try Exercise 06 (Bonus): deploy Prometheus + Grafana and observe your cluster and podinfo metrics in a live dashboard.

Otherwise, join the final presentation for a discussion on:

Why GitOps in production
What comes next: Vault, ApplicationSets, Argo Rollouts

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